1. Field of the Invention
The present invention relates to the field of amplitude and phase distortion circuits, and more particularly to phase distortion circuits for distorting the instantaneous phase of a signal.
2. Prior Art
RF amplifiers such as power amplifiers are typically subject to both phase distortion and amplitude distortion in the RF signal. Such distortion is characterized by increasing distortion at increasing instantaneous RF signal magnitudes. To reduce this distortion, the RF signal may be subjected to offsetting pre-distortion to try to negate the effects of the distortion. Similar effects can also be obtained by applying an offsetting post-corrective distortion to an already distorted RF signal. Preferably, independent control of phase distortion and amplitude distortion would be provided to simplify the pre-distortion or post-distortion process and improve its effectiveness.
An ideal phase distorter would be a device that would alter the phase of a signal as a function of the signal's voltage/power level without affecting the amplitude. Presently the only known RF distorter is an RF gain/phase distorter which creates both amplitude and phase distortion as a function of the RF signal amplitude. The gain and phase distortion are not independent, which limits the improvement in performance these blocks can provide. The use of a pure phase distorter would allow for independent control of both phase and gain distortion to greatly improve their benefit to the RF system performance. Currently, independent gain distortion circuits are available, but independent RF phase distortion circuits are not.